My question is what's the maximum stable overclocking speed that you have managed to get on your Pi 4 or 400?
By stable I mean no lock-ups or spontaneous reboots or what not. Just rock-solid, stable Pi goodness, even when under heavy real-world workloads like video trans-coding, compiling code, large-file compression, gaming etc. (instead of just stressberry testing for 24 hours).
For example, on my Pi 4 8GB running 64-bit Raspberry Pi OS, I run stable at 2.35GHz, even with all 4-cores maxed out.
On my Pi 400, I can squeeze out a bit more speed and run stable at 2.36 GHz, even under heavy load (that huge heat-transfer plate and Stepping C0 SoC really helps).
While my Pi 4 8GB can boot and run seemingly well at first at 2.38GHz, it will soon lock up when I start watching Youtube or Netflix in Full HD. But at 2.35GHz, it's stable as a can be. Same goes for my Pi 400; boots up fine at 2.38GHz, keels over the minute I put it under even moderate load. But at 2.36GHz, it runs like a well oiled machine even under heavy loads.
I have seen some (dubious) claims on Youtube of users running their Pi 4s or 400s at 2.4GHz or higher. While they may have struck silicon lottery with their SoCs, I suspect what they are reporting is the output of a simple lscpu or are using a program like hardinfo (sudo apt install hardinfo) to show their Processor details. See the screenshot below of hardinfo misreporting 2.36GHz as 2.40GHz. That's some rounding error!
Instead, I rely on the output reported by watch -n 1 "vcgencmd measure_clock arm" for greater accuracy.
I use the following commands to show me a continuously updated reading of the CPU's speed as it goes up and down on demand, the CPU's temperature, the voltage used and the throttled status, plus memory consumption for good measure:
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watch -n 1 "vcgencmd measure_clock arm && echo && vcgencmd measure_temp && echo && vcgencmd measure_volts && echo && vcgencmd get_throttled && echo && free -h"
Below are the settings I use on my Pi 400's /boot/config.txt file (I use the same settings for my Pi 4 8GB except I change arm_freq=2350).
This is shared here for information purposes only.
Your Pi may not be able to reach these speeds due to differences between manufacturing batches of the BCM2711 SoC.
If you are new to overclocking your Pi, maybe try a more conservative max clock speed setting like arm_freq=2000 and over_voltage=6, then iterate it up from there. Note that setting over_voltage=16 will result in no boot, so 15 is the highest setting you can dial it up to.
Note: If you set too aggressive overclocking settings and your Pi gets stuck and fails to boot, try doing a hard reboot and hold down the Shift key during startup. This bypasses the /boot/config.txt and allows you to get back to the Desktop to undo the changes. Alternatively, plug the boot media (microSD or SSD) into another computer and edit the /boot/config.txt from there.
*** WARNING: Overclocking your Pi 4 or 400's CPU at these extreme speeds may shorten the operating life of your Pi. Try at your own risk ***
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Has anyone on this forum managed to get 2.4GHz (or higher) with their units and if so, has it been stable under heavy real-world loads?